1. Field of the Invention
The present invention relates to a vehicle, such as a pickup truck or sport utility vehicle, having a torsion bar for assisting the closure of a tailgate or other door or closure panel mounted for rotation about a generally horizontal pivot axis.
2. Disclosure Information
Tailgates used with large pickup trucks and sport utility vehicles present a challenge to the motorist insofar as the weight of such tailgates and the height of such vehicles frequently results in the necessity of expending considerable effort to close the tailgate. U.S. Pat. No. 5,358,301, which is illustrated in FIG. 5, discloses a torsion bar system for assisting the closure of a tailgate. Unfortunately, the system disclosed in the '301 patent suffers from several drawbacks. First, the system would have high cost because the torsion bar is itself used as a hinge pin and this necessitates that the torsion bar be sufficiently large to not only function in torsion, but also in shear, so as to support the tailgate itself. Secondly, the fact that the torsion bar functions not only as a torsion element but also as a pivot for tailgate means that in the event that the torsion bar breaks, the tailgate's pivot function may be impaired, with the result that the tailgate could separate from the vehicle in a unwanted manner.
Because a torsion bar according to the present invention may be formed as a relatively thin and flexible member, road-induced vibration could cause audible noise as a result of the torsion bar striking a tailgate or other door to which it has been incorporated. An isolator according to the present invention prevents a “hard” strike of the closure panel by the torsion bar, thereby either eliminating, or at least greatly attenuating, the noise occasioned by the strike.
A torsion bar tailgate lift assist system according to the present invention solves the problems inherent in the previously described prior art system, but at a lower cost, while providing a torsion bar which is full floating, yet quiet during operation of the vehicle. As used herein, the term “full floating” means that if the torsion bar of the present inventive system were to break, the pivoting function and retention of the tailgate to the body of the pickup truck would not be adversely affected for as long as the driver leaves the tailgate upon the vehicle, because the tailgate pivots will function perfectly well without any intervention by the torsion bar.